Milli-Voltmeter, D.C. - Weston Electrical Instrument Co

Written for Brought to Light by: David Morris. Student Research Group: David Morris, Daniel Torode.

Black rectangular instrument housed in wooden box, which has leather strap handle.

This particular Milli-Voltmeter, Model 1 number 37259, was acquired by the University in 1922 for the Department of Physics. It was purchased for laboratory, service, and maintenance use on Campus and may also have been used by the department of Engineering.

The meter was manufactured in the Weston Laboratories, Newark N.J, and was standardised in 1922. The Weston model was first introduced in 1888 and remained in production until circa 1955. Edward Weston (1850 -1936) was the founder of the company and a prolific inventor who held 334 technological patents. The Model 1 was the first development of a precise, direct reading and portable instrument to electrical current and served as the foundation for modern multi-meters. The chassis of the instrument is likely to be a derivative of nitrocellulose, Celluoid or Bakelite, non-conductive early industrial plastics, that replaced previous wood and metal chassis that were prone to rot and weathering.

Voltmeters, in general, are used to measure voltage in electrical circuits. This voltmeter works when direct current (DC) flows through a coil of copper wire. This coil generates a magnetic field, and this field acts against another magnet. The two magnetic fields repel each other, and twist the coil. The coil pushes against a spring, and this moves the pointer which indicates voltage.

Did you know? It only takes 42 volts to stop the human heart, and it can take 200 -1,700 volts to restart it! Most household appliances run on 120 volts.